https://secure.wikimedia.org/wikipedia/en/wiki/Talk:Causes_of_autism#Neanderthal_Admixture_Hypothesis

” That’s because there may not have been a gene which made humanity, but a subtle complex of numerous genetic and cultural changes which transitioned at a critical point.”

I think this is the most likely scenario. The genetic changes may have been not only new alleles but also a greater frequency of alleles that were already present in the Neandhertal. This is similar to the fact that African people are adapted to malaria: it’s not only that they have specific gene adaptations, it’s that they have a bigger proportion of alleles that help to resist malaria (these alleles are present in other populations but with a lesser frequency, because natural selections don’t favor them).

Anyway, how do we know that early modern humans were that different from the Neandhertal? If I am not wrong, the “great leap forward” was about 40,000 years ago, when culture is supposed to have been created. Maybe the early modern humans were very similar to Neandhertal and it was only about 40,000 years ago that the genetic and cultural changes happened and this made a difference.

I’ve always considered that the principal difference between those two was the technology available to them. (one of the few advantages to life in the palaeolithic was that the technology for mass murder was comparatively restricted.)

just something i threw out. i have no idea what the difference is.

In any event, I might sooner hypothesize that followership (including features such as mirroring, empathy, and docility) is a more likely substrate of human success.

The consequences were similar to Razib’s thinking, although the “humans” managed to win in the end.

Don’t we see this with celebrities? Someone who goes from struggling musician to global rock-star, or waiter to movie star. Does being shown constant respect and admiration change neural architecture? Is it just the plasticity of our brains? As more people defer to us and respect us, our neural pathways devoted to discerning and deferring to the goals of other people wither, and the pathways devoted to expressing our own goals grow.

If the critical mass Razib refers to needed to change from 80% prevalence in Neandertals to 95% prevalence in moderns, they’ll need lots of genetic samples to work it out.

The role of memetic/cultural evolution makes things even murkier – what if it was a cultural change/innovation that made it all happen, and not easily traceable to genetics? While we’re clearly genetically distinct from Neandertals and I think it’s highly likely to have made a difference, what happened in Africa is less clear.

This could have to do with diet, pathogen resistance, or behaviors not directly related to intelligence, such as aggression or fearfulness

sure. but the thing that seems to weight it to something cognitive is the weird encephalization of the lineage. humans are to some extent sui generis. but our diet or immune system don’t seem qualitatively special. i’m not saying i know the solution, but i’m thinking we need to suspect it isn’t quite banal or typical, because it doesn’t seem like sentient hyper-cultural species are very common in the history of earth.

My own guesses (borrowed mostly from others): what gave raise to modern humans is not so much about cognitive abilities, but our ability to live in larger groups at higher densities. This could have to do with diet, pathogen resistance, or behaviors not directly related to intelligence, such as aggression or fearfulness. While we’re extraordinarily efficient at large-scale violence in recent eras, individual humans are, by most mammalian standards and certainly by primate standards, extraordinarily conflict averse (i.e. the domestication hypothesis).

What I always wonder about the supposed extinction of the neanderthals at the hands of modern humans is this: why are people so sure that the neanderthals were hunted nearly to death, and not just absorbed into the modern population? in central asia, for ex., we don’t assume that the earlier European types were completely wiped out by the later arriving Asians, we know they mixed together to create the populations we see today.